Home  l  Contact Us  l  Search
  General Description
  Hollowcore Types
  Design Specifications
  Technical Specifications

Hollowcore slabs are produced in standard width of 1200mm. Special width and cutouts can be made under certain conditions.

Dimensions and tolerances are shown in the table below:




Up to 4.5 m
4.5 m to 6 m
6.0 m to 12 m
>12 m

+ 10 mm
+ 12 mm
+ 18 mm
+ 24 mm

Width bottom

1200 mm

+0 mm
-3 mm


150 mm
200 mm
240 mm
265 mm
320 mm
400 mm
500 mm

+3 mm
-7 mm

Width of part slab


+ 20mm

Flatness (maximum deviation from 1.5m straight edge)


+ 20mm


Calculated value

+ 50 %

Variation in camber closely associated units


9 mm

Positions of strands (Maximum deviation from position)


5 mm

Size and positions of cut-outs as required with respect to detailed structural analysis


+ 20mm

Noise reduction (dB):

Noise reduction properties of Hollowcore Slabs are according to the following table:
(for details of noise reduction reference is made to BS 8233, 1987)




HCS 150:
50 dB

HCS 150+75 mm Screed: 54 dB

200 mm:
55 dB

HCS 200:
53 dB

HCS 200+75 mm Screed: 57 dB

250 mm:                    
57 dB

HCS 240: 
55 dB

HCS 240+75 mm Screed: 60 dB

290 mm:                    
60 dB

HCS 265:
56 dB

HCS 265+75 mm Screed: 61 dB

320 mm:
61 dB

HCS 320: 
58 dB

HCS 320+75 mm Screed: +62 dB

350 mm:                    
62 dB

HCS 400:
60 dB

HCS 400+75 mm Screed: 65 dB

450 mm:                    
65 dB

HCS 500:
63 dB

HCS 500+75 mm Screed: 68 dB

560 mm:                    
67 dB


Fire resistance

Hollowcore slabs elements meet the very highest requirements for non – flammability and fire resistance. For fire rating of prestressed concrete elements reference is made to BS 8110:part 1 1997, section

Slab Joint
The joints between the slabs can be filled without the need of shuttering.

Under normal conditions the Hollowcore slabs will need a minimum bearing not less than 60mm.

Bearing will, under normal conditions, always be designed as 75mm in order to allow for tolerances in the main load bearing structure. For spans more than 12m, the designed bearing should be 100mm due to the increased tolerances.

For erection on concrete beams, cast in-situ or block walls, a 18 mm joint is required to take the variances of the level of the support and secure a uniform bearing stress.

For erection on steel structure, the slabs can be placed directly on the steel beams or on a strip of roofing felt or similar.

Nominal and minimum bearings depend on the loading conditions and type of construction. Please contact the Design Departments at your respective locations for advise for specific project.

Joint reinforcement
Reinforcement can be placed in the joints to act as a horizontal structure bracing if required.

Using voids for services
Electrical conduits can easily be installed through the voids after erection of the slabs is planned correctly.

[ View Technical Details ]